An atomic-level platform for probing intertwined orders in correlated quantum materials (ImagingQM)

Correlated Quantum Materials (CQM) encompasses a large variety of materials systems in which electronic correlations and/or topology yield exotic physics, such as unconventional superconductors, multiferroic compounds, with novel magnetic and electronic orders. Engineering such materials through artificial thin film heterostructures and more generally symmetry breaking is a promising way to tailor their extraordinary properties. These efforts significantly rely on the guidance from spatially resolved characterisation of various orders (e.g. charge, lattice, orbital, spin) present in these CQM. To this purpose, however, the full potential of achieving sub-nanometre scale or atomic resolution, particularly in epitaxially strained single-crystalline thin films, is still yet to be unleashed. In this project, we aim to leverage several technical achievements to push the research frontier of study on ordering phenomena in CQM. This proposed research gains impetus from the strong need for atomic-scale disentanglement of the symmetry breakings and charge/spin orderings, which often happen at low temperatures, as well as the lack of available tools for direct visualization of the phase transitions and exotic phases in real space. We will commission and utilise the low temperature high-resolution scanning transmission electron microscopy (STEM) and spectroscopy (e.g., STEM-EELS) techniques (at both liquid nitrogen and liquid helium temperature ranges) for canonical and newly discovered paradigm oxide thin film systems, to assess and explore these exciting opportunities. In particular, we plan to make tremendous efforts in developing a unique approach to study the detailed electronic structure and various possible intertwined phases in superconducting nickelates, which were recently discovered by the Hong Kong PI. This project will establish a globally leading state-of-the-art low temperature electron microscopy infrastructure, specifically implemented for correlated quantum materials research. It helps gain significant new knowledge into the fundamental questions in condensed matter physics, such as the origin of high-temperature superconductivity, harnessing the world’s most advanced instrumentation and expertise through intimate collaboration, which are otherwise challenging to obtain by conventional techniques. The collaborative team will become a globally leading paragon of leveraging excellent electron microscopy for investigation of quantum mechanical and correlated effects in paradigm quantum materials.